The basic optics of dispersive and filter devices used to record the fluorescent spectra have remained relatively constant during the past several decades. A brief survey of the inventions in this field shows that there are few fundamental innovations in filters, prisms, wedges and gratings components used in this field of spectroscopy. In contrast there are hundreds of novel patents that concern innovative fluorescent tags and light sources to implement ever more specialized biological and chemical applications.
There has been some work in the field of fluorometers. Alfano (2001) disclosed an all-solid state fluorometer that uses either blue LEDs or red laser diodes as the exciting fluorescent sources. Lui and Li (1999) disclose a transmission grating fluorometer for DNA sample identification. Their method uses four dyes, one tag for each nucleotide. Kenny and Taylor (1996) disclose a fluorometer using a 3rd or 4th harmonic Nd:YAG laser. The emitting laser wavenumbers are 28200 and 37594 cm−1. They used a mixture of H2 and CH4 gas to Raman shift the laser light to the appropriate fluorescent dye excitation wavelengths. The spectral wavenumber options for excitation occur at integer multiples of these Raman shifts (about 3000 and 3600 cm−1); all wavenumbers lie below the Nd:YAG harmonic wavenumbers, such as 28200. cm−1.
Others have also used continuum spectral sources such as high-pressure Xenon gas sources and solid-state tungsten filaments to excite fluorescent dyes. This approach normally requires a monochronometer or other added filter to isolate the exciting wavelengths. Rasimas, Fehr and Hoots (2002) use a grating monochronometer to restrict the excitation wavelengths. Their device has the advantage of a being a tunable source, accomplished by turning the grating, if the spectral output is confined with a narrow exit slot. Giebler, Ogle and Kay (2001) use a similar exciting source; they also use a second grating monochronometer to measure the fluorescent light that arises from exposing the target sample to the exciting light. Other inventors, such as Kolber and Falkowski (2000) use a pulsing source to measure the time response of the fluorescent light. They do this using flashlets or brief flashes of light from a continuum Xenon source. This technique helps isolate the fluorescent source from the scattered light from the exciting source.
There is a need for a novel fluorometer that absorbs the light from the exciting source while transmitting the fluorescent light to the detector. This fluorometer must have higher dispersion than conventional optics so that the fluorometer can become as compact as the current microcomputers and have a high spectral resolution.
The following is a list of references, each of which is incorporated herein by reference:                Alfano, et al 2001 “Method for Using an All Solid State Fluorometer in an Industrial Water System Application”, U.S. Pat. No. 6,255,118, 3 Jul. 2001, Assignee: NALCO Chemical Company, Naperville, Ill.        (2)Kenny, J. and Taylor, T. 1996 “Method and System for Examining the Composition of a Fluid or Solid Sample Using Fluorescence and or Absorption Spectroscopy”, U.S. Pat. No. 5,491,344, 13 Feb. 1996, Assignee: Tufts Univ., Medford, Mass.        (3)Liu, C. and Li, Q. 2000 “Detector Having a Transmission Grating Beam Splitter for a Multi-Wavelength Sample Analysis”, U.S. Pat. No. 6,118,127, 12 Sep. 2000, Assignee: Spectrumedix Corp., State College, Pa.        (4)Rasimas, J. Fehr, M. and Hoots, J. 2002 “Modular Fluorometer”, U.S. Pat. No. 6,369,894, 9 Apr. 2002, Assignee: NALCO Chemical Company, Naperville, Ill.        (5) Giebler, R. and Ogle, D. and Kaye, R. 2001“Optical System for a Scanning Fluorometer”, U.S. Pat. No. 6,316,774, 12 Nov. 2001, Assignee: Molecular Devices Corp, Sunnyvale, Calif., See also U.S. Pat. No. 6,236,456, on 22 May 2001 by the same authors.        (6)Kolber, Z. and Falkouski, P. 2000 “Multiple Protocol Fluorometer and Method”, U.S. Pat. No. 6,121,053, 19 Sep. 2000, Assignee; Brookhaven Science Associates, Upton, N.Y.        